The initial objective of the proposed research is a detailed analysis of the nature of the passive immunity against oral infection that occurs in baby mice suckled by appropriately vaccinated mothers. Since ribosomal proteins (HS222), flagella and a vescicular material obtained during the isolation and purification of vibrio flagella are effective vaccines while killed cells and choleragen afford less protection, it will be important to determine whether the different responses are quantitatively or qualititively distinct. The contribution of motility to the pathogenesis of V. chorlerae will be evaluated in terms of the nature of the association between host intestinal mucosa and pathogen. This will serve as the approach to a broader attempt to understand the interplay between the role of toxin and of other bacterial products and structures to the initiation of the disease state. Suckling infant mice will serve as the experimental model.